l82 GENERAL PHYSIOLOGY 



lately if it is produced by a vigorous culture. This enzyme 

 can be easily isolated. It is called pyocyanase. 



It is probable that autolysis of bacteria takes place, in the 

 majority of cases, when the bacteria are lacking in some 

 requisite food product. It is the opinion of some investiga- 

 tors that, normally, the proteolytic (autolytic) enzymes are 

 held in check by the synthesis of the protein food materials 

 (Wells). There is also the probability that antienzymes 

 may be generated. 



Antienzymes. Enzymes, like other complex metabolic 

 products of bacteria, produce in the body fluids of immunized 

 animals, antibodies. Antienzymes for proteolytic enzymes 

 can be produced with the greatest ease. Antiamylolytic 

 and other enzymes are difficult to prepare. When com- 

 bined with the specific enzymes, either in vivo or in vitro, the 

 antienzyme renders the former inactive. Antienzymes can 

 be produced by the immunization of animals with enzymes 

 which have been subjected to heat at comparatively low 

 temperatures (enzymoids). The antienzymes are really 

 destroyed by a heat of 70 C. 



The most important products of metabolism are the poison- 

 ous substances which are produced by bacteria. These sub- 

 stances are known as the ptomains, toxins, endotoxins, and 

 the toxic bacterial proteins. These will be discussed in detail 

 in Chapter XXII. 



